patch 8.2.2006: .pbtxt files are not recognized

Problem:    .pbtxt files are not recognized.
Solution:   Recognize .pbtxt as protobuf text buffers. (closes #7326)
diff --git a/src/version.c b/src/version.c
index 2191c34..4b91ba4 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2006,
+/**/
     2005,
 /**/
     2004,